1. Field of the Invention
The present invention relates to a steel tube working apparatus that is especially available for repair of superheater tubes in a boiler, reheater tubes in the same, various types of heat-exchanger tubes, reinforcements, etc., and also to a clamping device, a welding device and a cutting device for use in the same steel tube working apparatus.
2. Description of the Prior Art
Describing now with respect to repair of a damaged location of a superheater panel constructed by arraying a plurality of tubes in a planar shape, by way of example, in a superheater of a boiler, as shown in FIG. 14 the superheater is formed by arraying several hundreds for each of superheater panels 01 at a narrow pitch. To the respective tubes forming the panel are connected pendant pipes 02, 03 and 04 by welding or mechanical means to hold the planar shape of the pane, and the pendant pipes are connected to a ceiling portion of the boiler to support the panel. An inlet header 05 consisting of a cylindrical pressure container and a similar outlet header 06 are secured by welding to the respective tubes in the panel so that they can be respectively communicated with each other. Steam is supplied from a piping system not shown to the inlet header 05 to be distributed among the respective tubes. After heat absorption has been effected, the steam is collected in the outlet header 06, and subsequently it drives turbines or other steam engines, or else it is used in a heating apparatus.
However, during use of the tubes in the above-described heater panel for a long period of time, damage would be generated therein due to aged deterioration or corrosion in material, and consequently, it becomes necessary to partly cut away the damaged tube and to substitute a new tube therefor. But, in the superheater, since the tubes are arrayed inherently in a thickly crowded state for the purpose of increasing thermal efficiency, for instance, since the tube interval within the superheater panel 01 is about 30 mm, an interval between the adjacent panels is about 60 mm, and thus the tubes are arrayed very close to each other, in the event that damage should arise at a certain portion of a group of tubes, it would be impossible for a worker to obtain access to the damaged location, and in such a case, it has previously been necessary to employ a method in which a superheater panel 01a including the damaged tube is cut away at its connecting portions 07 with pendant pipes 02a, 03a and 04a and the respective headers 05 and 06, respectively, then the cut panel 01 is hanged up and removed as by a winch not shown, and subsequently, after the damaged tube has been repaired, the panel 01 is restored to the original position. Accordingly, in the above-described method in the prior art, for only one damaged location it was necessitated to cut sound pendant pipes and amount portions between the panel and the headers at several tens of locations and to again weld all the cut locations after completion of repair of the damaged locations for restoring the panel to its original location. To the end an enormous time and expense was spent for repair of only one damaged location, and moreover, there was a problem that quality and reliability of the superheater itself was greatly degraded due to cutting, and welding for restoration of essentially sound portions.